如何使用FBO改善glTexImage2D性能

Question

I implemented an opengl-es application running on mali-400 gpu. I grab the 1280x960 RGB buffer from camera and render on gpu using glTexImage2D.

However the glTexImage2D call takes around 25 milliseconds for 1280x960 resolution frame. It does extra memcopy of pCameraBuffer.

1) Is there any way to improve the performance of glTexImage2D? 2) Will FBO help? how can I use Frame Buffer Objects to render. I found few FBO examples, but I see that these examples pass NULL to glTexImage2d in last argument (data). so how can I render pCameraBuffer with FBO?

below is the code running for each camera frame.

glGenTextures(1, &textureID);
glBindTexture(GL_TEXTURE_2D, textureID);

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, SCENE_WIDTH, SCENE_HEIGHT, 0, GL_RGB, GL_UNSIGNED_BYTE, pCameraBuffer);

glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
glDeleteTextures(1, &textureID);

Answer 1

The usual approach to this type of thing is to try and import the camera buffer directly into the graphics driver, avoiding the need for any memory allocation or copy at all. Whether this is supported depends on a lot on the platform integration, and the capabilities of the drivers in the system.

For Linux systems, which is what you indicate you are using, the route is via the EGL_EXT_image_dma_buf_import extension. You need a camera driver which creates a surface backed by dma_buf managed memory, and a side-channel to get the dma_buf file handle into the application running the graphics operations. You can then turn this into an EGLImage using the extension above.